Gear testing machine



.Fuly 19, 1%38. c, OLSON 2,124,119

GEAR TESTING MACHINE Filed Feb. 8, 195'? 3 Sheets-Sheet 1 July 19, 1938. 7 QG, OLSQN 2,124,119

' GEAR TESTING MACHINE Filed Feb. 8, 1957 a Sheets-She et 2 001% G: 0&6021/ @a a 9,

July 19;, 1938. c. G. OLSON GEAR TESTING MACHINE Filed Feb. 8, 1957 3 Sheets-Sheet 3 Patented July 19 1938 UNITED STATES PATENT OFFICE 2,124,119 GEAR 'rns'rmo mcnma Carl G. Olson, Chicago, IlL, assignor to Illinois Tool Works, Chicago, 111., a corporation of Illinois Application February a, 1937, Serial No. 124,592

More specifically, my invention contemplates a testing machine, as set' forth above, wherein a 10 beveled gear to be tested may in effect be rolled upon the base cone from which the involute curves of the teeth are generated. a

It is an object of the invention to provide a machine, as set forth above, whereby beveled gears 15 of various sizes may be-tested with a minimumdegree of effort and skill on the part of the user.

Still more specifically, this invention contemplates a testing machine, as set forth above,

wherein a cone base member conforming with. 20 the base cone of the gear to be tested may be rolled along a plane surface to enable a contactor positioned in the vicinity of the involute surface of the gear to accurately detect any-variation in said surface from the true involute.

25 The foregoing and numerous other objects and advantages will be more apparent from the following detailed description when considered in connection with the accompanying drawings, wherein:

Figure 1 is a front elevational view of a machine constructed in accordance with the teachings of the present invention with a bevel gear in section shown in operative association. with the contactor;

Figure 2 is a viewof the machine shown in. Fig-- ure 1 as viewed from the right thereof;

Figure 3 diagrammatically illustrates the man'- ner in which the involute surface of the gear may be tested by rolling the gear along its base or gen- 40 erating circle, two positions of the gear being shown, one at the left and the one at the right;.

Figure 4 is a diagrammatic representation of the principle upon which the machine of Figures 1 and 2 operates; I r I 45 Figure 5 is a front elevational view disclosing the'manner in which the machine of Figure 1 may be adjusted to accommodate a bevel-gear differing in angularity with respect to the gear shown in Figure 1;

50 Figure 6 discloses the machine of Figure 1 accommodating a bevel gear considerably larger than the bevel gears shown in Figures 1 'and 5;

Figure '7 is an enlarged fragmentary detail view of the lower or bearing extremity of the gear 55 and roller supporting spindle, a portion thereof being broken away to more clearly illustrate the manner in which the ball is secured and centered within said spindle;

Figure 8 discloses a modified bevel gear testing machine wherein the gear to be tested and the 5' base cone member are positioned on opponte sides of the pivotal point;

Figure 9 is a fragmentary view of the machine shown in Figure 8, said view being taken from the rightof Figure. 8, the base cone member being in- 0 dicated by doteand-dash lines whereby to 'render visible parts otherwise hidden Figure 10 is a detailed fragmentary view of-the universal mounting structure, said view being taken along the line l0 -i0 of Figure 8; and 1 Figure 11. illustrates in cross section, a frag,- mental-y portion of a base cone member of modifled formin operative association with a plane I surface.

Before discussing the structural details of the machine illustrated in the. drawings representing embodiments of the invention, it should be borne in mind that the involute surface ofa gear tooth is generated from a base or generating circle. v This is best illustrated in Figure 3 wherein a gear 5 blank, indicated generally by the numeral .II, has its generating circle indicated by the numeral 14. Thus, when the gear I! is roiledalong a plane surface l8 as, for example, from the left in Figure 3 'to the position shown at the right in Figure 3, the contactor l8 touchingthe involute surface 20 of a gear tooth 22, will experience no lateral displacement if the surface 20 conforms in curvature with the true involute. However, any slight variation from the true involute will cause the contactor it to experience slight lateral displacement and such displacement may be magnified for observation on a suitable indicator later to be described- From the foregoing explanation it will be ap-. parent that the base circle or member I! of a" conventional spur gear comprises a cylinder, and hence may correctly be referred to as a base cylinder, having its axis indicated by the numeral 24 (Figure 3). Referring now to Figure 4,

it will be seen that I have disclosed a cone gear blank I21: and a cone base member Ila, which correspond, respectively with the elements I! andit of Figure'3. In practice the gear member Ila obviously is provided with the usual bevel gear V teeth, but, for the purpose of illustration, the teeth have been omitted, leaving only that portion of the gear which is encircled by the imag-L 'inary base or generating cone of the gear. The

gear |2a cannot actually be rolled along its base roll along its generating conical surface in the same sense as the generating circle l4 of the gear l2 rolls along the surface l6. In view of the fact that it is only necessary to impart a slight degree of rotation to the gear blank |2a for the purpose of testing same with a contactor, such as the contactor l8 in Figure 3, the surface l6a may be a surface as indicated by the dotted lines 5b in Figure'4. v I

With the foregoing statement of the theory of operation of the conical base cone l4a with respect to the gear l2a in mind, reference is now made tothe testing machine of Figures 1 and 2 designated generally by the numeral 21. This machine incorporates a suitable bed 28 which supports a machine base 30. A horizontally disposed bar or rod 32 is supported at one end above the base 30 in a bracket or support 34, which will hereinafter -be referred to as the indicator support because this support carries a dial type indicator mechanism designated generally by the'numeral 36. A second support 38 for the bar 32, which supoprt will hereinafter be referred to as the spindle support, is adapted to be horizontally adjusted along a V-guide 40. The upper portion of the spindle support 38 provides a bearing or socket 42.

The socket 42 is designed to receive an apex ballmember 44 secured to the lower end of a spindle 24b, the center 26b of the ball 44 being coincident with theaxis of said spindle. This spindle 24b serves as a support or carrier for a bevel gear-to be tested-for example, the bevel gear l2b in Figure 1. A shoulder 46 on the spindle 24b prevents downward displacement of the gear l2b, the upper portion of the gear being engaged by a suitable spacing collar 48. Engaging the opposite side of the collar 48 is a roller [41), which may be referred to hereinafter as a base cone member. The base cone member I; and gear IZbare clamped together by means of a suitable knurled head 52, which is screwed upon the reduced outer threaded extremity 54 of the spindle 24b. This head 52 in addition to serving as V a clamping element, provides a gripping surface adapted to be engaged when rotary movement is to be imparted to the base cone memher [4b, as will hereinafter more clearly appear.

The peripheral conical or frusto-conical surface of the base member l4b rests upon a horizontal plane surface or track 16b, said surface corresponding with the surface l6b. diagrammatcially illustrated by the dotted lines in Figure 4. This plane surface l6b is provided along the upper surface of a block or plate 56, which in turn is horizontally slidable upon the upper por-' 'screw (not shown) may be adjustably positioned along said rod. A

suitable set screw 64 serves to secure the contactor in the desired position, and a keyway 66- cooperates with a complementary section on the contactor to maintain the contactor in its normal upright position. A suitable set screw 68 serves to secure the work engaging portion or point of the contactor in its proper vertical position. The point at which thecontactor l8b actually engages the involute surface of the tooth of the bevel gear I 2b is indicated by the letter A. It will be noted that the center or apex 26b, the point A, and the plane surface or track [6b all lie in the same horizontal plane, and this plane is tangent to the imaginary base cone of the bevel gear I2b, the roller or base cone member l4b cooperating with the plane surface [6b and the apex 26b in causing the gear I2b in effect to roll along the imaginary peripheral surface of the base cone thereof when rotation is manually imparted to the knurled head 52.

The contactor ND is operatively connected with the dial indicator mechanism 36 through the rod or-bar 32 and an actuating arm 10 secured to and extending upwardly from the rod 32 in the vicinity of the indicator supporting bracket 34. The upper or free extremity of the arm ID has a contactor ball 12, which engages the shiftable element 14 of the dial indicator mechanism 36, as clearly indicated in Figure 2. The

tendency for the member I4 to shift to the left (Figure 2) under the influence of the spring mechanism within the indicator means 36 insures continuous engagement of the contactor l8b with the complementary tooth of the supported gear.

From the foregoing description it will be apparent that when the bevel gear I21) and the base cone member l4b are mounted in the position previously explained, namely, with the apex 26b, the plane surface I61), and the contactor point A positioned in the same plane, the testing of the gear I 2b may be started. To insure engagement of the contactor point A with the involute surface of the gear tooth, the wheel 62 may be rotated slightly so as to bring the involute surface of the gear into engagement with the contactor point A. "This will cause movement of the indicator needle (not shown) of the indicator mechanism 36 and said mechanism may be set at a zero point from which point variations in surface contour of the gear tooth may be observed. After the indicator has been so set, rotation may be imparted to the knurled head 52, thereby causing the base cone member l4b to roll along the plane surface I617. This causes the imaginary base cone of the bevel gear l2b to roll along a plane coincident with the plane surface 16b. If the surface of the gear tooth conforms with the true involute curve, no. -movement will be experienced by the indicator l2b. However, all variations from the true involute will be visually apparent upon the indicator mechanism 36. This test may be repeated for each tooth of the gear at various points along the tooth surface.

' To similarly test the opposite sides of' the gear teeth, it is only necessary to loosen the' set screw 66 and impart a turn to the upper portion of the indicator l8b so as to position the point A for engagement with the opposite sides of the gear teeth. The dial indicator mechanism 36 is mounted upon an arm 16 which may be swiv- A, the indicator mechanism is shifted 180 to the dot and dash position indicated on Figure 2. The

previously described testing operation is again repeated until all of the. gear teeth have been examined, if so desired.

In order to accommodate bevel gears of varying size and angularity the supports or blocks 38 and 58 are adjustable along the V-guide' 40 and a T slot l8.- By turning a' handle 80 of the support 38 and a similar handle 82 of the support 60, said supports may be positively secured in their desired position of adjustment upon the base 30. Attention is also directed to the fact that I prefer to provide a ball bearing 84 so as to render the baror-rod 82 freely movable;

Referring now to Figure 5, it will be seen that the above described testing-machine is adapted to be used for a bevel gear which varies in angul'ari-ty from the bevel gear l2b.- In Figure 5 a bevel gear I20 is mounted upon a spindle c which functions exactly the same as the previously described spindle 24b, except that it is longer in order to take care of the difference in angularity between the bevel gear I20 and the bevel gear l2b. A base cone member He, smaller than the base cone member Mb, is employed. .With the exception of the use of an intermediate or auxiliary support 88 for the rod' rolled alongan imaginary plane tangent thereto in the same manner as described in connection with Figures 1 and 2. I

Figure 6 discloses the testing machine equipped vwith a shorter spindle 24d designed to accommodate a larger bevel gear iZd and a larger base cone member Hd.- With this arrangement of the spindle and base cone member, bevel gears of the larger variety having an angularity differing from the angularity-of. the bevel gears lib and He may be tested. In Figure '7 I have fragmentarily shown the lower end of one of the gear supporting spindles which is broken away to more clearly illustrate the manner in which the apex ball 44 is secured by means of a screw 92 against an internal conical surface 84 provided within the lower end of the spindle. This arrangement enables the ball to automaticallybeen positionedon the same side of the pivot point or apex. Referring now to Figure 8, it will be seenthat I have shown a modified machine wherein a gear lie to be tested and a base cone member He are positioned on opposite. sides,

of a pivotal point or axis 26c, which axis corresponds with the apex 26b previously described.

Instead of employing the ball and socket arrange-- merit previously described, a universal joint arrangement designated generally by the numeral. 96H-in-Figures8 to 10 inclusiveis 'employed.

mechanism 96 carries the spindle Ileand through the agency of a yoke 88 and an upright supporting structure I00 the spindle He may be tilted about the horizontal and vertical axes indicated in effect the spindle 24c swivels about'thecenter" or apex 28a in the same sense as the spindle '21P swivels about the apex 28b and the spindle 24a swivels about the apex 26a. The peripheral, surk by the dot and dash lines in Figure 1.0.1

face of the base cone member-He en ages a ye tical plane surface We which is carried by't All:

upright supporting structure Hill.

An actuator Be is provided which is pivoted at its intermediate point M2. The left extremityf of the actuator is adapted to contact the involute surface of the teeth of the bevel gear I 2e, and the opposite extremity is adapted to be engaged by the actuating mechanism of,a conventional dial indicator means 36c which corresponds with the indicator means 88 previously described. Anarm i is vertically adjustable within the upright frame structure I08 and serves as a support for both the contactor l8e and the indicator means 36c. It will be noted that the dial indicator means tie is carried upon an auxiliary arm iilii which may be swivelled through 90 upon the arm' or bracket I 'so as to enable the indicator to be used in indicating variations in the involute contour of both sides of the gear teeth. The contactor lie is. so designed as to enable the tooth engaging portion thereof to be swivelled through 90 When it is understood that the point of engagement of the contactor i 8e with the teeth of the bevel gear He, the apex or swivel point He, and the plane surface lie all lie in the same plane, it will be clear that, when rotation is imparted to the base cone member lle along the surface lie by manually manipulating a knurled head He, the imaginary base or generating cone of the bevel gear lie will roll along a vertical.

plane tangent thereto, which plane includes the apex 28 and the plane surface We The machine disclosed in Figures 8 and 9 is equipped with a vernier scale I88 which cooperates with an arm 0 connected with the yoke 88 in accurately determining the angular setting of the axis of the spindle 24c. This angular setting of the axis of the spindle 24c must be in absolute accordance with the angularity of the gear to be tested so as to cause said gear to roll on its imaginary base or generating cone.

The plane surface lie is provided on-a plate 56::

which is adjustable transversely of the machine through the manual manipulation of a handwh'eel 82a. The shifting of the plate 56c corresponds with the shifting of the plate 58 previously' described in connection with Figures 1 and 2.

Attention is also directed to a horizontal surface H2 and a gauge roller H4, which is carried-at the lower extremity of the adjusting arm -.l.'ill.v

He differs in peripheral contour from .thef1: re-- viously described base cone members in that it face 6 which conforms with the frustrumsof .is provided with an intermediate peripheral :surr' I a cone.; whose apex is positioned at He and curved peripheral surface sections H8 and J20 positioned on opposite sides of the intermediate section'l l6. With this arrangement the machine 'can be used to test gears in which the angularity and size will permit the use of the intermediate peripheral surface section I I6, and will also permit gears of other size and angularity to be measured by bringing the peripheral surface section H8 or I28 into engagement with the plane surface Ilie. Obviously when the inclination or angularity of the axis of the arbor Me is varied from that shown in Figure 8, axial adjustment of the base cone member He along the arbor must be made. It will be noted that the knurled member 52c, in addition to serving as a handwheel, also provides sufficient weight to maintain proper engagement of the base cone member with the plane surface iGe.

In Figure 11 I have fragmentarily disclosed in cross section the lower portion of a base cone member M] of modified form wherein the entire peripheral surface thereof is curved in cross section, as distinguished from the arrangement disclosed in Figure 8. The curved surface arrangement permits the member II! to be angularly adjusted with respect to its complementary plane surface l6].

From the foregoing it will be apparent that the invention contemplates a gear testing machine particularly adapted for bevel gears which comprises relatively few parts, is easy to manipulate, and may be produced by the practice of conventional machine shop methods. -The machine is so designed as to enable a very accurate examination of the bevel gear teeth to determine variations from the true involute curve. The uniof a bevel gear tooth surface differs from the involute curve of a spur gear in that the bevel tooth surface is a compound curve. This is due to the fact that the bevel gear surface is generated by a point in a cone rolling on a flat surface and not by a cylinder rolling on a flat surface. A point'in the surface of a cone rolling on a flat surface does not follow a straight line of said surface as is the case when a cylinder rolls on a flat surface, and this introduces a compound curve in the bevel gear tooth. In other words, the true involute curve of a bevel gear tooth is globular. It may, be said that a bevel gear tooth surface comprises a globular segment. While certain specific structural details have been disclosed herein for the purpose of illustrating my invention, it should be understood that said invention is by no means limited to these specific structural arrangements, but is capable of other modifications and changes without departing from the spirit and scope of the appended claims. a

Having thus described my invention, what I claim as new and desire to secure by Letter Patent is:

1. Gear testingapperatus including contactor means for engaging a gear tooth, a plane surfaced member,-a roller having its. peripheral surface engaging said plane 'surfacathe axis of said roller being inclined with respect to said surface, and means for supporting a gear in coaxial relation with said roller whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to-roll upon the generating surface thereof while one of the teeth of said gear remains in engagement with said contactor, thereby causing the contactor to move in case said tooth is out of true.

2. Gear testing apparatus including'contactor means for engaging a gear tooth, a plane surfaced member, a roller having its peripheral surface engaging said. plane surface, the axis of said roller being inclined with respect to said surface, the tooth engaging portion of said contactor lying in a plane coincident with said plane surface, and means for supporting a gear in co-axial relation with said roller whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to roll upon the generating periphery thereof while one of the teeth of said gear remains in engagement with said contactor, thereby causing the contactor tov move in case said tooth is out of true.

3. Gear testing apparatus including contactor means for engaging a gear tooth, a plane surfaced member, a roller having its peripheral surface engaging said plane surface, the axis of said roller being inclined with respect to said surface, and means for supporting a gear in coaxial relation with said roller and having a pivotal axis of support positioned in a plane coincident with said plane surface whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to roll upon the generating circle thereof while one of the teeth of said gear remains in engagement with said contactor, thereby causing the contactor to move in case said tooth is out of true. t

4. Gear testing apparatus including contactor means for engaging a gear tooth, a plane surfaced' member, a roller having its peripheral surface, and means for supporting a gear in coaxial relation with said roller and having a pivotal support axis positioned in a plane coincident with the plane which includes the tooth engaging portion of said contactor and said plane sur-" face whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to roll upon the gen-- erating circle thereof while one of the teeth of said gear remains in engagement withv said contactor, thereby causing the contactor to move in case said tooth is out of true.

5. Gear testing apparatus including contactor means for engaging a gear tooth, a plane surfaced member, a roller having its peripheral surface engaging said plane surface, the axis of said roller being inclined with respect to said surface, means for supporting a gear in co-axial relation with said roller whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to roll upon the generating circle thereof while one of the teeth of said gear remains in engagement' with, saidcontactor, thereby causing the contactor to move in case said tooth is out of true, and means for indicating movement experienced by the contactor.

6. Gear testing apparatus including contacto means for engaging a gear tooth, a plane surface engaging said plane surface, them of said roller being inclined with respect to said surface, and pivotally supported means for support- .surface engaging said plane surface, the axis of ing a gear in co-axlal relation with said roller 70 faced member.- a roller having its peripheral sura on the same side of the pivotal axis as said roller whereby to cause saidgear, when relative movement is experienced between said roller andplane surfaoe, in efiect to roll upon the generating circle thereof while one of the teeth of said gear remains in engagement with said contactor. thereby causing the' contactor to move in case said tooth is out of true. 7

7. Gear testing apparatus including 'contactor means for engaging a gear tooth, a plane surfaced member, a roller having its peripheral surface engaging said plane surface, the axis of said roller being inclined with respect to said surface, and pivotally supported means for sup porting a' gear in co-axial relation with said roller on the opposite side of the pivotal axis Q whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to roll upon the generating circle thereof while one of the teeth of said gear remains in engagement with said contactor, thereby causing the contactor to move in case said tooth is out of true.

8. Gear testing apparatus including contac means for engaging a gear tooth, a plane surfaced member, a roller having itsperipheral surface engaging said plane surface, the axis arcane of said roller being inclined with respect to said surface, and means for supporting a gear in co-axial relation with said roller whereby to cause said gear, when relative movement is experienced between said roller and plane surface, in effect to roll upon the generating circle thereof while one of the teeth of said gear remains'in engagement with said contactor, thereby causing the contactor to move in case said toothis out of true, said gear supporting means being adjustable to vary the, inclination of the roller axis with respect to said plane surface. 7

9;. Gear testing apparatus including contactor means for engaging a gear tooth, a plane sur faced member. a roller having a peripheral conical surface engaging saidjplane surface, the axis of said roller being inclined with respect to said surface, and means for supporting a gear in c'o-axial relation with said roller whereby to I cause said gear, when relative movement is ex: perienced-between said roller and plane surface, inwefiect tc roll upon the generating circle thereof while one of the teeth of said gear remains in engagement with said contactor. thereby causing the contactor to move in case said tooth is.

out-cf true.

w CARL G. OLSON. 

